Desiccated pig thyroid (natural T4 and T3 pig thyroid) is best tried after T4 synthetics at several different levels has been proven to not relieve your symptoms.
Now this may seem strange to the majority who have symptoms relief from just synthetic T4........those people are lucky.
When starting any desiccated thyroid med; like Armour, Erfa, NP thyroid or Nature Throid bands (they have 2), start low and ramp up 15mg per week or two weeks. This info used to be on the Armour website PDF.
Starting at your full does will usually make you too edgy, sweaty, temp hyper due to your body getting used to the direct T3. This will also happen with synthetic T3 Cytomel.
After the FDA forced Armour and Nature Throid to revamp their fillers in 2009, the T4 became less absorb-able and thus increased the ratio of T4 to T3 in users blood even further than the ratio pig thyroid in known for.
ERFA and NP Thyroid have slightly closet T4 to T3 rations than the other due to a different filler and are the closest thing to the older (better) pre 2009 Armour.
Most Endos will prefer T4 only, simply because thats what they are trained in. Most Natural Path MD's will prefer natural if T4 alone does not work for you.